All across tropical Australia, the arrival of these gigantic alien toads has caused massive die-offs among meat-eating animals such as yellow-spotted monitors (large lizards in the varanid group) and quolls (meat-eating marsupials). Mistaking the new arrivals for edible frogs, animals that try to eat them are fatally poisoned by the toad’s powerful toxins.

Steep population declines in these predators ripple out through entire ecosystems.

But we can change that outcome. We expose predators to a small cane toad, big enough to make them ill but not to kill them. The predators learn fast, and ignore the larger (deadly) toads that arrive in their habitats a few weeks or months later. As a result, our trained predators survive, whereas their untrained siblings die.

So as we cruised across the floodplain on quad bikes looking for goannas, each team consisted of a scientist (university-educated, and experienced in wildlife research) and a Balanggarra Indigenous ranger.

Although our study species is huge – a male yellow-spotted monitor can grow to more than 1.7 metres in length and weigh more than 6kg – the animals are well-camouflaged and difficult to find.

Over an 18-month study, we caught and radio-tracked more than 80 monitors, taught some of them not to eat toads, and then watched with trepidation as the cane toad invasion arrived.

Excitingly, the training worked. Half of our trained lizards were still alive by the end of the study, whereas all of the untrained lizards died soon after toads arrived.

That positive result has encouraged a consortium of scientists, government authorities, conservation groups, landowners and local businesses to implement aversion training on a massive scale (see www.canetoadcoalition.com), with support from the Australian Research Council.

A yellow-spotted monitor fitted with a radio transmitter in our study. This medium-sized male was trained and lived for the entirety of the study in high densities of cane toads.Georgia Ward-Fear, University of Sydney

Cross-cultural collaboration key to success

But there’s a twist to the tale, a vindication of our decision to make the project truly collaborative.

When we looked in detail at our data, we realised that the monitor lizards found by Indigenous rangers were different to those found by western scientists. The rangers found shyer lizards, often further away from us when sighted, motionless, and in heavy cover where they were very difficult to see.

Gregory Johnson, Balanggarra elder and ranger.Georgia Ward-Fear

We don’t know how much the extraordinary ability of the rangers to spot those well-concealed lizards was due to genetics or experience – but there’s no doubt they were superb at finding lizards that the scientists simply didn’t notice.

And reflecting the distinctive “personalities” of those ranger-located lizards, they were the ones that benefited the most from aversion training. Taking a cautious approach to life, a nasty illness after eating a small toad was enough to make them swear off toads thereafter.

In contrast, most of the lizards found by scientists were bold creatures. They learned quickly, but when a potential meal hopped across the floodplain a few months later, the goanna seized it before recalling its previous experience. And even holding a toad briefly in the mouth can be fatal.

Comparisons of conditions under which lizards were initially sighted in the field by scientists and Indigenous rangers (a) proximity to lizards in metres (b) density of ground-cover vegetation (>30cm high) surrounding the lizard (c) intensity of light directly on lizard (light or shade) (d) whether the lizard was stationary or moving (i.e. walking or running). Sighting was considered more difficult if lizards were further away, in more dense vegetation, in shade, and stationary.Georgia Ward-Fear, University of Sydney

As a result of the intersection between indigenous abilities and lizard personalities, the overall success of our project increased as a result of our multicultural team.

If we had just used the conventional model – university researchers doing all of the work, indigenous people asked for permission but playing only a minor role – our project could have failed, and the major conservation initiative currently underway may have died an early death.

So our study, now published in Conservation Letters, provides an unusual insight – backed up by evidence.

Moving beyond lip service, and genuinely involving Indigenous Traditional Owners in conservation research, can make all the difference in the world.

Increased urbanisation has made it more difficult to connect with nature. And members of lower socioeconomic and minority ethnic groups, people over 65 and those living with disability are less likely to visit green spaces. This could be due to inaccessible facilities and safety fears.

A gardening program for disadvantaged groups, running in New South Wales since 1999, has aimed to overcome the inequity in access to green spaces. Called Community Greening, the program has reached almost 100,000 participants and established 627 community and youth-led gardens across the state.

Our independent evaluation explored the program’s impact on new participants and communities in social housing by tracking six new garden sites in 2017. Around 85% of participants told us the program had a positive effect on their health and 91% said it benefited their community. And 73% said they were exercising more and 61% were eating better. One participant said engaging in the program even helped them quit smoking.

These insights have advanced our understanding of how community gardening improves the mental and physical health of Australians living in social housing communities in our cities.

Our research investigated these outcomes in participants, and whether they changed during the course of the program. We collected data using questionnaires over seven months (before and after participation). We also conducted focus group interviews with participants and open-ended questionnaires with staff working at the community sites.

Of the 23 people who completed both questionnaires before and afterwards, 14 were female and nine were male. They had an average age of 59, ranging from 29-83. Fifteen participants were born in Australia while the rest came from Fiji, Iran, Poland, New Zealand, Philippines, Chile, Afghanistan and Mauritius. One participant identified as an Aboriginal and/or Torres Strait Islander and five people (22%) reported English was not their first language.

Initially, 27% reported they had never gardened prior to the program. At the post-test questionnaire, the frequency of attendance improved for many of them. Over 40% gardened once a week and 22% every day.

Gardening benefits

Overall, we found participants felt a sense of agency, community pride and achievement. The gardening program helped encourage change and community development. Some were happy to learn a new hobby.

Community Greening participants found a lot of benefits to gardening.Research infographic/Screenshot, Author provided

Gardening also served as an opportunity to socialise with neighbours. In previous years within some social housing communities, it was commonplace for residents to simply stay inside their units without interacting with anyone.

Many participants said they saw a marked improvement in their health and well-being. One participant remarked:

I suffer with a lot of health problems, and a lot of times I’ve been sitting at home, been depressed and not been happy about my illness, and since I’ve become more involved with the garden it helped me to not worry about my health so much like I used to and it actually improved my eating habits. It has changed my life positively. I don’t have time to feel sorry for myself anymore…

Some described the gardening experience as calming and cathartic – especially those who suffered from depression and anxiety. Some spoke of the positive aspect of having something to do each day and their feelings of achievement.

Another participant said:

Going outside gives me not only physical exercise, but it provides a certain amount of joy in that you’re seeing the benefit of your hard work coming through in healthy plants. Whether it’s vegetables or a conifer, you’re seeing it grow and you’re seeing the benefit…

Additional improvements in social health included a genuine enthusiasm for working in a team, with increased co-operation and social cohesion between staff and tenants. The housing managers and social workers work alongside tenants helping to foster trust, co-operation, social collaboration and healthy relationships.

More importantly, this research has provided validation that Community Greening has aligned with contemporary social-housing priorities. These include supporting health and well-being, nurturing a sense of community, enhancing safety and developing a sense of place.

Urban bushland has health benefits beyond being a great place to go for a walk. It filters our air and water, helps cities avoid extremes in temperatures, and is linked to lower rates of chronic disease.

But these and other health benefits are virtually never accounted for in local and state land development processes.

Urban planners need to consider these health benefits when making decisions about the future of our cities.

What do we mean by urban bushland?

Urban bushland ranges from a bush park of native trees, to wetlands – in fact any native vegetation characteristic of the local region. With its undisturbed soils and associated wildlife, urban bushland is more diverse than other types of green spaces in our cities, like parks. So it adds significantly to neighbourhood biodiversity.

The more unfragmented the landscape, or unaltered the bushland, the more likely it will be to retain its biodiversity. Hills, watercourses and gullies, or a mixed forest, have greater biodiversity than flat land or a plantation of trees. Landscapes that change by the season add to that diversity.

In cities, health benefits work at two levels. Not only do local residents receive health benefits when they use urban green spaces, the wider urban population also feels the health effects.

Healthy locals

The closer residents live to green space, particularly if it is accessible or usable, the better they report their health.

For an individual, access to green spaces contributes in multiple ways: it reduces stress, it helps us recover from illness or injury, and our thinking abilities improve when we are more contemplative and mindful of our green surroundings.

The quality of green spaces plays a role in the health benefits for locals. For example, views of diverse vegetation more effectively lowers stress compared with less-diverse vegetation.

Exposure to biodiversity from the air, water, soils, vegetation, wildlife and landscape, and all the microbes associated with them (the sort retained in uncleared bushland and wetlands) enhances our immunity. This is thought to be the key to the health benefits of nature.

A recent review highlights the host of physical health problems that are reduced in urban areas with more nature, including less heart disease, obesity and diabetes. Mental health is also improved in urban areas where people are living with more green space.

Urban bushland, like this in the Western Australian city of Joondalup, provides health benefits to locals who access it and the wider population.Author provided

Urban bushland improves city water. Wetlands and the vegetation around them clean our water by filtering, reducing exposure to pollutants carried in groundwater or surface water run-off.

Shrinking urban bushland

Where new suburbs are developed on the outskirts of cities, the end result is usually near-complete clearing. Urban bushland is replaced with smaller, fragmented, more sanitised, open and neat spaces.

These are designed for a narrower (but still important) set of usable attributes, like a bike path, lawns and a playground. But the original values of the bushland are lost. This pattern is repeated in the expanding suburbs of cities across Australia.

If some urban bushland, wetlands or other landscape assets have been retained, the pressure on them from development is relentless, as seen recently in Western Australia where a highway is due to be extended through the Beeliar Wetlands.

Planning for better planning

Planning processes need to use ways to assess what we might lose and what we might gain from clearing bushland.

This could involve asking what types of services existing bushland provide for local residents and the city in general. These will include their role in providing clean air and water, controlling floods, cycling nutrients, as well as their recreational or spiritual services.

These could be compared with services the proposed development offers. The comparison should make decision makers, and more importantly the public, better able to judge the true worth or cost of a development.

Such cost-benefit analyses are usually used somewhere in planning processes but rarely, if ever, are the values of biodiversity and ecosystem services considered, or the cost savings from health benefits of bushland.

These sorts of cost-benefit analyses can also be used to account for the health effects associated with local bushland. Such health assessments (or health impact assessments) need to be more widely used. And where land subdivision, road building and suburban housing developments are planned, health assessments may need to be compulsory to better account for the contribution of urban bushland to health.